Semiconductor diodes having such a contacting system are known. Such semiconductor diodes comprise a circuit element body (silicon crystal), which is metallised on both major sides, which circuit element body is placed in a housing of soft glass. Apart from adhesion layers, use is generally made for this purpose on the front side of the crystal of a comparatively thick silver layer of large surface area (thickness about 5 to 20% of the thickness of the circuit element body, diameter more than 100 .mu.m) and on the back side of the circuit element body of a thin silver layer of large surface area. The silicon body is then sealed into a glass tube, two connection wires engaging the said silver layers with their end faces. If a heat treatment is carried out up to the softening point of the soft glass (about 700.degree. C.), the soft glass wets the sheath surfaces of the connection wires, while upon cooling the soft glass shrinks a little so that the connection wires are pressed against the silver layers.
Consequently, the circuit element body is electrically connected to the connection wires by pressure contacting. Upon sealing, the silver layers neutralize the occurring forces since the silver is deformed in an irreversible manner.
If a circuit element thus contacted is caused to operate at comparatively high temperatures and with frequent temperature variations, the problem arises that the thick silver metallization of large surface area has a considerably larger heat expansion than the silicon crystal covered thereby. With frequent strong temperature variations, shear stresses at the interface between the silicon and the silver may lead to such strong irreversible deformations of the metallization that the circuit element becomes defective. Furthermore, the temperature variation is also accompanied by pressure variations in the axial direction so that the metallization may be subjected to an axial creepage deformation. Finally, the resulting reduction in pressure may mechanically and electrically interrupt the connection between the metallization and the adjoining connection wire.
West German patent No. 3122387 discloses a glass diode which is metallized with titanium and copper. Furthermore, a tin layer is present, which upon sealing establishes a soldering connection of copper/tin/copper. The mechanical otherwise usual pressure contact is consequently replaced in this circuit element by a soldering connection.
A circuit element known from West German patent No. 2643147 is constructed in a similar manner, in which a gold/germanium layer on silver is used.
In the latter two known circuit elements, the risk of contact interruptions could be reduced with respect to the usual pressure contact. However, the problem of the lateral deformations explained above is not solved. Therefore, the invention has for its object to construct a contacting system of the kind mentioned in the opening paragraph in a manner such that it behaves in a mechanically and electrically stable manner at operating temperatures up to 300.degree. C. and with frequent temperature variations.